Silicon Carbide MOSFET Integrated Circuit Technology

Abstract

The research and development activities carried out to demonstrate the status of MOS planar technology for the manufacture of high temperature SiC ICs will be described. These activities resulted in the design, fabrication and demonstration of the World's first SiC analog IC — a monolithic MOSFET operational amplifier. Research tasks required for the development of a planar SiC MOSFET IC technology included characterization of the SiC/SiO2 interface using thermally grown oxides; high temperature (350 °C) reliability studies of thermally grown oxides; ion implantation studies of donor (N) and acceptor (B) dopants to form junction diodes; epitaxial layer characterization; N channel inversion and depletion mode MOSFETs; device isolation methods and finally integrated circuit design, fabrication and testing of the World's first monolithic SiC operational amplifier IC. These studies defined a SiC n‐channel depletion mode MOSFET IC technology and outlined tasks required to improve all types of SiC devices. For instance, high temperature circuit drift instabilities at 350 °C were discovered and characterized. This type of instability needs to be understood and resolved because it affects the high temperature reliability of other types of SiC devices. Improvements in SiC wafer surface quality and the use of deposited oxides instead of thermally grown SiO2 gate dielectrics will probably be required for enhanced reliability. The slow reverse recovery time exhibited by n+–p diodes formed by N ion implantation is a problem that needs to be resolved for all types of planar bipolar devices. The reproducibility of acceptor implants needs to be improved before CMOS ICs and many types of power device structures will be manufacturable.

Stacking faults in SiC crystal grown by spontaneous nucleation sublimation method

“…Silicon carbide is expected to replace Si or GaAs as high power or high frequency electronic devices and to enable new applications in extreme environments such as high temperature, strong radiation and chemical hazards due to its excellent physical and chemical properties [1][2][3]. However, commercial use of SiC for device applications, especially for high-power devices is still seriously limited by the lack of high-quality substrate materials.…”

Silicon Carbide Fully Differential Amplifier Characterized Up to 500 °C

“…The measured low offset and high linearity of this amplifier demonstrates that the SiC BJT technology is suitable for front-end sensor circuits for high-temperature applications. [4] 300 76 3000 0.6@50ºC;25@300ºC 6H-SiC NMOS [7] 300 53 269 -4H-SiC NMOS [8] 350 60 ~200 35@27ºC;150@350ºC 4H-SiC NMOS [9] 300 42 ~100 -4H-SiC NMOS [10] 500 55 ~1000 -6H-SiC JFET [11] 576 69 1400 *…”

“…Up to 300 ºC, Si-based CMOS amplifiers [3], [4] have demonstrated higher gain and gain-bandwidth than those in SiC NMOSFET [7]- [10]. Above 300 ºC, SiC dominates, and compared to the SiC JFET amplifier [11], lower offset and higher gain-bandwidth have been achieved in this work.…”

“…Its bandgap is almost three times that of Si, which results in low intrinsic carrier concentration, orders of magnitude lower than that of Si [1]. High-temperature MOSFET SiC amplifiers have been demonstrated in [7]- [10], in which the maximum operation temperature is 500 °C [10]. On the other hand, JFET SiC amplifiers can operate stably at ambient temperature up to 576 °C [11], [12] by eliminating gate oxide.…”

Fully-monolithic, 600°C differential amplifiers in 6H-SiC JFET IC technology

“…Maximum operating temperature for the SiC MOSFET amplifiers reported in [2], [3] is limited to 300 o C, due to unstable threshold voltages caused by poor gate oxide quality. On the other hand, the simple SiC JFET amplifier reported in [4] has a very stable voltage gain (less than 1% change) of ~3 after 3007 hours of operation at 500 o C. In this work, a family of fully differential JFET IC amplifiers that provide voltage gains up to 69 dB at 576°C is reported.…”